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Refuge Notebook: Black widows take terminal trips to Alaska

A specimen of the northern cobweb spider from the entomology collection of the Kenai National Wildlife Refuge. This individual is not as dark as usual and lacks the red markings typical of this species.

This image shows the Kenai specimen, with a detail of the hourglass pattern on underside of abdomen.

A black widow specimen from Kenai, taken in September 2013, is now in the Kenai National Wildlife Refuge's entomology collection.

As an entomologist, I am frequently asked whether or not we have any brown recluses or black widow spiders in Alaska. Although neither of these medically significant spiders is likely to become established in Alaska, it appears that black widows, at least, make it up here occasionally.

In 2002, an article in the Juneau Empire reported a black widow in Juneau that was found by airport workers handling imported siding.

In 2005, the Peninsula Clarion reported on a black widow in Kenai that was apparently brought in with lawn furniture.

In 2006, Jim Kruse, an entomologist serving the U.S. Forest Service, identified a black widow that had been found in grapes purchased at a grocery store in Fairbanks.

In November, 2008, Michael Rasy of the UAF Cooperative Extension Service collected a black widow from a garage in Anchorage.

This September, a live female black widow spider was brought to me from a house in Kenai by a resident that had correctly identified it as a black widow. The spider had set up her web under the lip of a plastic tote that had been moved up to Alaska from the Lower 48 months earlier.

Unfortunately, since I preserved this spider before it reached adulthood, I cannot identify which of the more than 30 species of widow spiders it is without resorting to DNA-based methods. It is probably one of the common, widespread North American widow spiders such as the western black widow, the southern black widow, or the northern black widow, which together naturally range from southern Canada to Florida and Mexico.

Although widow spiders are not likely to survive out-of-doors in Southcentral Alaska, it is possible that they could persist for a time in a protected situation. A number of other exotic arthropods are already established in our area living exclusively in man-made structures. For example, I have seen long-bodied cellar spiders from houses in Soldotna and Kenai, where they lived in garages and crawl spaces; the Nikiski Pool at one time had an infestation of Firebrats (a kind of silverfish); and the Visitor Center here at the Kenai National Wildlife Refuge houses a persistent population of dust lice (Badonnelia titei).

To the best of my knowledge, no brown recluses have been found in Alaska, but, like the black widows from Anchorage and Kenai, they could be brought here.

This April, multiple Alaskan news outlets reported on a large, living, exotic wandering spider (Ctenidae) that was found in a bunch of bananas in Ketchikan.

The overwhelming majority of spiders we encounter in Alaska, even in houses, are native, harmless, and unlikely or unable to bite people, though some of these can be mistaken for widows, recluses, or hobo spiders.

Steatoda borealis, sometimes called the northern cobweb spider, is a native cobweb spider related to black widows that is easily mistaken for one. It shares a similar overall appearance with widows in that it is glossy black with a large abdomen usually having red markings. It is smaller than a widow spider, though, and lacks the characteristic red hourglass pattern on the underside of its abdomen.

We also have several native brown spiders that could be mistaken for brown recluses. Of these, wolf spiders and funnel weavers commonly enter houses.

The recent importations of black widow spiders mentioned here highlight the growing influx of exotic flora and fauna to our decreasingly isolated state. Like the widows, most of these species do not survive here, but a few do. For example, the amber-marked leaf miner, the green alder sawfly, the gray garden slug, and several earthworm species are Old World animals that have successfully invaded Alaska through international and interstate movement of people and their things.

Introductions like these threaten to change our natural systems in unpredictable and potentially detrimental ways, which is why multiple state and federal entities in Alaska work to intercept, eradicate, or control exotic species.

Any Alaskans who find unusual spiders or insects that they think might be introduced, such as widows or brown recluses, can bring or mail them to their local University of Alaska Cooperative Extension Service office or to the University of Alaska Museum. Please include your name and contact information and details on the place and date of collection.

Matt Bowser serves as Entomologist at the Kenai National Wildlife Refuge. You can find more information about the refuge at http://kenai.fws.gov or http://www.facebook.com/kenainationalwildliferefuge.